connect to DB using SSH java

The SSH connection is to port 22. The local port for the tunnel should be a different, non-reserved port, e.g. 61521.

You then use the local address and port in the SQL*Net URL for the connection.

So showing only the relevant parts:

    int localPort = 61521;
    String remoteHost = "HostIp";
    int remotePort = 1521;
    ...
    try {
        java.util.Properties config = new java.util.Properties();
        JSch jsch = new JSch();
        session = jsch.getSession(sshuser, sshHost, 22);
        ...
        session.setConfig(config);

        session.connect();

        System.out.println("SSH Connected ...");

        int assinged_port =
            session.setPortForwardingL(localPort, remoteHost, remotePort);

        System.out.println("localhost:" + assinged_port + " -> " +
                           remoteHost + ":" + remotePort);

        try {
            Class.forName("oracle.jdbc.pool.OracleDataSource");

            conn = DriverManager.getConnection(
                       "jdbc:oracle:thin:@localhost:61521/service_name",
                       "DB User", "DB Pass");
        } catch (SQLException ex) {
        ...

In your SQL Developer screen shot, I would expect the first Host value to be your remote host, i.e. whatever `"sshHost" actually is in your code; which SSH contacts on port 22. The second Host and Port values are how the database listener is reached by the SSH session, not by you. ('localhost' there is the remote server; what it sees as local host, and reaches on loopback address 127.0.0.1). WIth the radio button selections, that SSH connection is allocating its own local port, and connecting to that, and you don't really need to know what value that has.

In your code, this call:

jsch.getSession(sshuser, sshHost, 22);

this is the equivalent of the first Host and Port in the SQL Developer dialog. Again, sshHost is the value in that first Host box.

Then this call:

session.setPortForwardingL(localPort, remoteHost, remotePort);

is the equivalent to the second Host and Port section in your SQL Developer screenhot. Here, remoteHost is the Host value, probbaly localhost; and remotePort is Port value, which is 1521.

Where this differs from the SQL Developer set-up is the localPort value. In SQL Developer that is being auto-assigned (because you have 'automatically assign local port' selected). In your code you are specifying is yourself, and it's that value that has to be a non-reserved port.

So with just the relevant parts, you do something like:

jsch.getSession(sshuser, 'your_remote_host', 22);
session.connect();
session.setPortForwardingL(61521, 'localhost', 1521);
DriverManager.getConnection(
                   "jdbc:oracle:thin:@localhost:61521/service_name"

It may be a bit confusing that there are two references to localhost and that they seem to mean slightly different things. That's because it's a special loopback address that stays within the computer (hence 'local'). You can think of the first one (in setPortForwaringL) as the remote server's internal reference to itself; and the second one (in the getConnection()) as your PC's internal reference to itself.

It's even more confusing that your screenshot shows localhost for both Host values. If that's what you really have then it doesn't make much sense and you shouldn't need SSH at all. So, I imagine you changed the real value to hide it for posting, and just picked a confusing fake value, instead of using sshHost or hostIP or similar.